Reconfigurable shape memory polymer tooling supports

ABSTRACT

A method and support apparatus for providing structural support to a mold or mandrel, such as a shape memory polymer (SMP) apparatus configured for shaping a composite part. The support apparatus may comprise a rigid structural member and a plurality of SMP cells attached thereto and configured to inflate or deploy in a malleable state toward and against a surface of the SMP apparatus, mold, or mandrel. Then the SMP cells may be returned to a rigid state while still pressed against this surface, thereby providing structural support when composite material is applied to an opposite surface of the SMP apparatus, mold, or mandrel. After the composite material is cured into the finished composite part, the SMP cells may be deflated or otherwise collapse toward the structural member to provide enough clearance to be removed from the cured composite part.

RELATED APPLICATIONS

The present utility patent application claims priority benefit, withregard to all common subject matter, of earlier-filed U.S. provisionalpatent application titled “Reconfigurable Shape Memory Polymer ToolingSupport” Ser. No. 61/412,627, filed Nov. 11, 2010, hereby incorporatedin its entirety by reference into the present application.

BACKGROUND

1. Field

The present invention relates to systems and methods for using areusable apparatus made of shape memory polymer (SMP) to fabricatecomposite parts.

2. Related Art

Composite parts, such as those used in the manufacture of aircraft, canbe constructed using various production methods, such as filamentwinding, tape placement, overbraid, chop fiber roving, coating, hand layup, or other composite processing techniques and curing processes. Mostof these processes use a rigid cure tool/mandrel on which compositematerial is applied and then cured into a rigid composite part. Removingthe mandrel from the cured composite part is generally difficult,costly, and/or time-consuming, particularly if the resulting compositepart has trapping geometry that precludes easy part removal. One knownmethod of removing the mandrel requires sacrificing or destroying themandrel by cutting, dissolving, bead-blasting, or otherwise breakingdown the mandrel into smaller pieces which can be removed from withinthe composite part. Destroying the mandrel obviously prevents it frombeing used again for subsequent parts and can be damaging to an innersurface of the composite part.

Another method uses a segmented mandrel that can be disassembled andremoved after the composite part is cured. However, these mandrels areexpensive and require a great amount of time to install and remove.Furthermore, these segmented mandrels are typically each designed tofabricate a specific composite part and are not easily reconfigured tobe used in the manufacture of other composite parts.

Yet another method uses inflatable mandrels that can be removed bydeflating them after the composite part is cured. However, this methodtypically involves balloon-like mandrels that can only be used as abagging aid due to their relative lack of strength and rigidity duringcomposite lay-up.

Accordingly, there is a need to structurally support inflatable orformable mandrels during the forming of a composite part.

SUMMARY

Embodiments of the present invention include a support apparatusconfigured for providing internal support to a mold, tooling, or a shapememory polymer (SMP) apparatus for forming composite parts. The supportapparatus may comprise a rigid structural member, a plurality ofinflatable or deployable SMP cells inflatable or deployable throughopenings in the rigid structural member, and a pressurization systemconfigured to inflate or deploy the SMP cells to extend from the rigidstructural member. Specifically, the SMP cells may be made of shapememory polymer (SMP) configured to be actuated to transition between arigid state and a malleable state. For example, the SMP cells may beconfigured to be rigid at temperatures below T_(g) and to becomemalleable at temperatures above T_(g). The rigid structural member maybe configured to remain rigid when heated to a temperature sufficientfor curing a composite part. The pressurization system may inflate ordeploy the SMP cells when the SMP cells are in the malleable state. Whencooled in the inflated configuration, the SMP cells may be configured toprovide a load path between the SMP apparatus and the rigid structuralmember during application of composite material onto the SMP apparatus.

A method of forming a composite part on an SMP apparatus composed of SMPmaterial may comprise placing a support apparatus proximate to at leastone surface of the SMP apparatus. The support apparatus may comprise arigid structural member, a plurality of inflatable or deployable SMPcells extending from the rigid structural member and actuatable betweena rigid state and a malleable state, and a pressurization systemconfigured to inflate or deploy the SMP cells away from the rigidstructural member. The method may further comprise actuating the SMPcells to the malleable state and then inflating or deploying the SMPcells with the pressurization system such that the SMP cells pressagainst the surface(s) of the SMP apparatus while in the malleablestate. The method may also comprise actuating the SMP cells to the rigidstate while the SMP cells are pressed against the surface(s) of the SMPapparatus, thus providing a rigid load path between the SMP apparatusand the rigid structural member. Then the method may comprise applyinguncured composite material to another surface of the SMP apparatusopposite of the surface(s) of the SMP apparatus in contact with the SMPcells.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the detaileddescription. This summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter. Other aspectsand advantages of the present invention will be apparent from thefollowing detailed description of the preferred embodiments and theaccompanying drawing figures.

DESCRIPTION OF DRAWING FIGURES

Embodiments of the present invention are described in detail below withreference to the attached drawing figures, wherein:

FIG. 1 is an end view of a support apparatus constructed in accordancewith an embodiment of the present invention, illustrating the supportapparatus inside of a shape memory polymer (SMP) apparatus wrapped withcomposite material;

FIG. 2 is an end view of the support apparatus of FIG. 1 extended intoan inflated and deployed configuration, pressing against the SMPapparatus;

FIG. 3 is a schematic diagram of the support apparatus of FIG. 1including a rigid structural member, an SMP cell, and a pressurizationsystem of the support apparatus;

FIG. 4 is a top perspective view of an alternative embodiment of thesupport apparatus, illustrating the rigid structural member and aplurality of the SMP cells;

FIG. 5 is a perspective view of another alternative embodiment of thesupport apparatus with a fragment removed, illustrating a plurality ofdeployable and invertible SMP cells extending from a tray of the rigidstructural member;

FIG. 6 is a perspective view of the support apparatus of FIG. 5,illustrating an alternative embodiment of the SMP cells;

FIG. 7 is a perspective view of a plurality of the SMP cells of FIG. 6;

FIG. 8 a is a fragmentary, perspective end view of the support apparatusof FIG. 6 illustrating the SMP cells in a deployed configuration;

FIG. 8 b is a fragmentary, perspective end view of the support apparatusof FIG. 6 illustrating the SMP cells in an inverted configuration;

FIG. 9 is a side elevation view of another alternative embodiment of theSMP cells for the support apparatus of FIG. 5;

FIG. 10 is a perspective view of another alternative embodiment of thesupport apparatus, wherein the SMP cell has an elongated length; and

FIG. 11 is a fragmentary, perspective end view of the support apparatusof FIG. 6 illustrating the SMP cells in a deployed configurationpressing into the SMP apparatus.

The drawing figures do not limit the present invention to the specificembodiments disclosed and described herein. The drawings are notnecessarily to scale, emphasis instead being placed upon clearlyillustrating the principles of the invention.

DETAILED DESCRIPTION

The following detailed description of the invention references theaccompanying drawings that illustrate specific embodiments in which theinvention can be practiced. The embodiments are intended to describeaspects of the invention in sufficient detail to enable those skilled inthe art to practice the invention. Other embodiments can be utilized andchanges can be made without departing from the scope of the presentinvention. The following detailed description is, therefore, not to betaken in a limiting sense. The scope of the present invention is definedonly by the appended claims, along with the full scope of equivalents towhich such claims are entitled.

In this description, references to “one embodiment”, “an embodiment”, or“embodiments” mean that the feature or features being referred to areincluded in at least one embodiment of the technology. Separatereferences to “one embodiment”, “an embodiment”, or “embodiments” inthis description do not necessarily refer to the same embodiment and arealso not mutually exclusive unless so stated and/or except as will bereadily apparent to those skilled in the art from the description. Forexample, a feature, structure, act, etc. described in one embodiment mayalso be included in other embodiments, but is not necessarily included.Thus, the present technology can include a variety of combinationsand/or integrations of the embodiments described herein.

As illustrated in FIGS. 1-2, some embodiments of the present inventioncomprise a support apparatus 10 configured to provide structural supportto a mold, tooling, or a shape memory polymer (SMP) apparatus 12, suchas one of the hollow SMP apparatuses described in the followingco-pending U.S. Patent Applications: U.S. application Ser. Nos.13/238,695; 13/238,879; 13/238,733; 13/238,841, and 13/238,775, eachincorporated herein by reference in their entirety. These incorporatedapplications disclose some embodiments of the SMP apparatus 12 beingused as a rigid mandrel for composite material lay-up and then beingtriggered to change to a malleable state to be inflated during cureand/or to be removed from the composite part after cure. When used inthis manner, the SMP apparatus 12 generally must be thin enough to formeffectively, but also stiff enough to resist deflecting underout-of-plane loading imposed by the force of automated composite lay-upequipment such as filament winders and tape laying machines. It is alsogenerally desirable for the SMP apparatus 12 to have sufficientstructural stiffness to resist bending under its own weight and theweight of the composite material placed thereon. The need for the SMPapparatus 12 to be thin for forming conflicts with the structuralstiffness requirements for composite material application. Thus, thesupport apparatus 10 is designed to structurally support the SMPapparatus 12 for forming a composite part so that the SMP apparatus 12does not collapse under the weight of the composite material 14 or thepressure applied when placing the composite material 14 on the SMPapparatus 12, while still keeping the SMP apparatus 12 dimensions withina formable range.

SMP Apparatus

The SMP apparatus 12, as illustrated in FIGS. 1-2, may be formed of SMPmaterial cast into any memory shape. For example, the SMP apparatus 12may be cast into an elongated and/or hollow configuration having one ormore open ends using any method known in the art, such as methods offorming an SMP cylinder disclosed in U.S. Pat. No. 7,422,714,incorporated by reference herein in its entirety. For example, the SMPapparatus 12 may be a pre-formed SMP cylinder or barrel open at twoopposing ends. Alternatively, the SMP apparatus 12 may have anycross-sectional shape, such as a trapezoid, rectangle, square, ortriangle, or may be cast into a non-hollow configuration. The castedshape of the SMP apparatus is referred to herein as its memory shape.

The SMP material used to form the SMP apparatus 12 may be reinforced orunreinforced SMP material. Specifically, the SMP material used to formthe SMP apparatus 12 may be an epoxy, an epoxy-based SMP, a styrenecopolymer based SMP or any other type or combination of SMPs, such ascyanate ester, polyurethane, polyethylene homopolymer,styrene-butadiene, polyisoprene, copolymers of stearyl acrylate andacrylic acid or methyl acrylate, norbonene ordimethaneoctahydronapthalene homopolymers or copolymers, and malemide.For example, the SMP material used in the SMP apparatus 12 may be any ofthe SMPs described in U.S. Pat. Nos. 7,422,714, 6,986,855, 7,276,195,U.S. Patent Application Publication No. 2008/0021188, U.S. PatentApplication Publication No. 2008/0021166, and/or U.S. Patent ApplicationPublication No. 2008/0269420, all of which are incorporated herein intheir entireties by reference. However, numerous other types of SMPsexist and can be tailored to meet specific tolerances and temperaturerequirements.

The modulus of various SMP materials can be changed through severaldifferent methods, such as a temperature change, an electric current,water, and/or light. However, the exemplary methods described hereindisclose the use of temperature changes to transform the SMP apparatus12 from a malleable state to a rigid state and vice versa. Nevertheless,any of the above-listed triggers or actuation techniques for changingthe modulus of the SMP material of the SMP apparatus 12 may be used forthe composite part fabrication methods described herein withoutdeparting from the scope of the invention.

A glass transition temperature (T_(g)) of an SMP material may be athreshold temperature at and/or above which that SMP material maytransition to a lower modulus state, become softened and/or malleable inorder to be deformed. Therefore, the SMP apparatus 12 of the presentinvention may be configured to become flexible and formable when it isheated above its T_(g) and to become rigid when cooled to a temperaturebelow its T_(g). If the SMP apparatus 12 is deformed at a temperatureabove T_(g) and then held in that deformed state as its temperaturedrops below T_(g), then the SMP apparatus 12 may harden in that deformedstate. When heated again, the SMP apparatus 12 may return to itsoriginally-casted memory shape unless otherwise acted on by anotherforce.

The SMP apparatus 12 may be made of an SMP material having any T_(g)appropriate for the uses and methods described herein. In someembodiments of the invention, T_(g) may be equal to or less than thecuring temperature for the composite material 14, such that the SMPapparatus 12 may be used as an expandable bladder during curing of thecomposite part. In some embodiments of the invention, T_(g) may be atemperature between 100° F. and 350° F. Furthermore, T_(g) may be atemperature between 200° F. and 300° F. or between 225° F. and 275° F.In one embodiment of the invention, T₉ may be approximately equal to250° F. For example, the change in modulus of the SMP apparatus 12 mayoccur within a small temperature range centered at a T_(g) ofapproximately 250° F.

The composite material 14 placed on the SMP apparatus 12 to form thecomposite part may comprise or be in the form of prepreg, wet processedfiber, dry fiber, continuous fiber, discontinuous fiber, chopped fiber,low temperature resin, high temperature resin, toughened resin, glass,KEVLAR, carbon, and/or core. Furthermore, the chemical makeup of thecomposite material 12 may include epoxy, BMI, benzoxazine, and othersimilar substances known in the art. The composite material 14 may beplaced onto the SMP apparatus 12 using automated fabric placement,automated fiber placement, automated filament winding, fabric placement,hand lay-up, or any other method known in the art. The compositematerial 14 may be configured to be hardened or cured, such as in anautoclave, out of an autoclave, via a low-temperature cure process,and/or via a high-temperature cure process.

In use, the SMP apparatus 12 may be actuated or triggered to itsmalleable state, formed into the mandrel configuration, then actuated,triggered, or otherwise allowed to return to its rigid state, such as bycooling the SMP apparatus 12 below T_(g). Next, the composite material14 may be applied thereon. For example, in its malleable state, the SMPapparatus 12 may be shaped by inflation or any induced pressuredifferential driving the SMP apparatus 12 toward a mold. Specifically,the SMP apparatus 12 may be placed inside the mold, outside the mold,and/or proximate to a surface of the mold in order to be driven towardand shaped by the mold. Specifically, the SMP apparatus 12 may be heatedand inflated or otherwise deformed into a mandrel configuration forforming a surface (such as an inner surface) of a composite part. Oncethe SMP apparatus 12 is cooled or otherwise converted to its rigid statewhile in the mandrel configuration, as illustrated in FIG. 1, thecomposite material 14 may be placed thereon using any method known inthe art, such as fiber placement or filament winding.

The SMP apparatus 12 may be used to form a variety of composite parts,such as aircraft fuselages, wings, nacelles, panels, ducts, and aircraftstructural supports or stiffeners. Examples of aircraft structuralsupports may include stringers, frames, trapezoidal hat-shapedstiffeners, bell-shaped stiffeners, inverted hat stiffeners,J-stiffeners, F-stiffeners, blade stiffeners, I-stiffeners,C-stiffeners, and various types of core, such as honeycomb core.Additionally, the SMP apparatus 12 may be used to form a variety ofother composite parts, such as trailers, automotive ducts and manifolds,hoses, tires, turbochargers, tanks, automobiles, racing vehicles, boats,yachts, bicycles, canoes, kayaks, paddles, sporting goods, gun stocks,grips, crossbows and accessories, golf clubs and related components,fishing rods, guitars, pipes, poles, building supplies, wind turbineblades, engine components, furniture, sail masts, electronic enclosures,armor, driveshafts, satellites, missiles, and spacecraft. Thesecomposite parts may be formed using methods similar to those describedabove.

Each of these composite parts may be formed using the SMP apparatus 12by first forming the composite material 14 against at least a portion ofthe SMP apparatus 12 when the SMP apparatus 12 is in its rigid mandrelconfiguration. Then the composite material 14 may be compressed byinflation or expansion of the SMP apparatus 12 during curing of thecomposite material 14 into the composite part. Alternatively, the SMPapparatus 12 may remain rigid in its mandrel configuration during curingof the composite material 14 into the composite part, while an externalapparatus, such as a vacuum bag or impermeable membrane, compresses andconsolidates the composite material 14 against the SMP apparatus 12.

Support Apparatus

As illustrated in FIGS. 1-6, the support apparatus 10 may be configuredfor use during a step of forming of the SMP apparatus 12 into themandrel configuration and/or during the step of forming the compositematerial 14 against the SMP apparatus 12 in its rigid mandrelconfiguration. Specifically, the support apparatus 10 may be configuredto fit inside of or underneath the SMP apparatus 12. Additionally oralternatively, the support apparatus 10 may be positioned to contact atleast one surface of the SMP apparatus 12 opposite of a surface thereofonto which the composite material 14 is to be placed.

As illustrated schematically in FIG. 3, the support apparatus 10 maycomprise a rigid structural member 16, a plurality of SMP cells 18attached to, sealed to, and/or extendable from the structural member 16,and a pressurization system 20 configured to inflate and/or deploy theSMP cells 18 in a direction away from the structural member 16 when theSMP cells 18 are in the malleable state. Inflation or deployment of theSMP cells 18 while in their malleable state may allow the SMP cells 18to conform to a portion of an inner surface of the SMP apparatus 12 andthen hardened or returned to their rigid state while thus conformed, asdescribed below. The support apparatus 10 thus provides internalstructural support to the SMP apparatus 12 when composite material isapplied to an outer surface of the SMP apparatus 12. For example, insome embodiments of the invention, this may prevent the SMP apparatus 12from collapsing or deforming during filament winding of compositematerial onto the SMP apparatus 12.

The rigid structural member 16 may have any shape or configuration andmay be formed of a material that remains rigid when subjected tocomposite cure temperatures and pressure. The structural member 16 maybe configured to support attachment and/or sealing of the SMP cells 18thereto. In some embodiments of the invention, the structural member 16may have one or more openings formed therethrough, over which the SMPcells 18 may be sealed and through which inflation pressure may beprovided to the SMP cells 18.

The SMP cells 18 may be formed of the same SMP material as the SMPapparatus 12 or any other SMP material known in the art and desired fora particular application. The T_(g) of the SMP cells 18 may be identicalto the T_(g) of the SMP apparatus 12, or alternatively the SMP cells 18may be composed of SMP material having a different T_(g) than the SMPapparatus 12. The SMP cells 18 may be flat, contoured, and/or hollow andmay be shaped in a variety of configurations. In some embodiments of theinvention described herein, the SMP cells 18 may comprise a peripheralor edge portion sealed to the structural member 16. Additionally, asmentioned above, the SMP cells 18 may each be sealed around and/or overone of the openings formed through the structural member 16, such thatpressure applied through the openings may inflate and/or deploy the SMPcells 18.

In some embodiments of the invention, as illustrated in FIG. 3, thepressurization system 20 may comprise tubes 26 and a pressure source 28.The tubes 26 may be any sort of air or liquid delivery system, such ashollow pipes connected between the pressure source and the SMP cells 18.The pressure source 28 may be configured to fluidly communicate with thetubes 26 and to force liquid, air, or other gasses into portions of therigid structural member 16, the tubes 26, and/or to the SMP cells 18.For example, the pressure source 28 may be any sort of air pump or aircompressor manually and/or electrically actuated. Additionally oralternatively, one or more of the SMP cells 18 may be configured to beinflated via pressurization of an autoclave (not shown). However, anymethod for inflating or deploying the SMP cells 18 by way of inducedpressure differential may be used in the methods described hereinwithout departing from the scope of the invention.

In some embodiments of the invention, the heating of the SMP cells 18may be achieved by insertion into an oven or an autoclave. Additionallyor alternatively, in some embodiments of the invention, thepressurization system 20 may comprise a heat exchanger 30, asillustrated in FIG. 3, which may be configured to heat the liquid, air,or other gasses provided by the pressure source 28. In these embodimentsof the invention, a venting and circulation system (not shown) may bepart of and/or fluidly coupled with the pressurization system 20. Forexample, heated liquid, air, or gasses may be circulated into the SMPcells 18 and vented out of the SMP cells 18 via the venting andcirculation system. In some embodiments of the invention, the liquid,air, or gasses vented out of the SMP cells 18 may be re-circulated intothe heat exchanger to be reheated and pumped back into the SMP cells 18.Heating the liquid, air, or gasses used to inflate the SMP cells 18 mayallow better forming of the SMP cells 18 against the inner surface ofthe SMP apparatus 12.

Support Apparatus—Spoke and Bladder Configuration

In one embodiment of the invention, as illustrated in FIGS. 1-3, therigid structural member 16 may comprise a center structural support 22and a plurality of extension support members 24. For example, theextension support members may be arranged in a spoke-like configurationrelative to the center support structure 22. The center supportstructure 22 may be an elongated cylindrical member or an elongatedrigid structure having any cross-sectional shape. The extension supportmembers 24 may be elongated and may extend substantially perpendicularrelative to the center support structure 22. For example, if the centersupport structure 22 has a circular cross-section, the extension supportmembers 22 may extend perpendicular to a tangent of the circularcross-section.

In some embodiments of the invention, the extension support members 24may each be extendible and/or retractable, having amechanically-adjustable length. For example, the extension supportmembers 24 may be operable to telescope toward or away from the centersupport structure 22 either manually or by way of some automatedactuation (e.g., a hydraulic cylinder). This feature may allow thesupport apparatus 10 to be used in SMP apparatuses of a large variety ofconfigurations or sizes and/or may facilitate removal of the supportapparatus 10 from within the SMP apparatus 12 by retraction of theextension support members 24.

Furthermore, in embodiments of the invention illustrated in FIGS. 1-3,the plurality of SMP cells 18 may be SMP bladders each formed of SMPmaterial, as defined above. In this embodiment of the invention, the SMPcells 18 may be substantially hollow with an opening formed therein forfluid communication with the pressurization system 20. As illustrated inFIGS. 1-2, the SMP cells 18 or bladders may each be attached to one ofthe extension support members 24. The SMP cells 18 may be operable to beinflated when heated above T_(g) or otherwise triggered to the malleablestate. For example, inflation may be provided by forcing pressurized gasinto the SMP cells 18 via their respective openings formed therein, orusing any other inflation means known in the art.

The pressurization system 20 may be fluidly coupled with the SMP cells18 in a variety of configurations. For example, in one embodiment of theinvention, the central support structure 22 and/or the extension supportmembers 24 may be substantially hollow, providing direct delivery offorced liquid or pressurized gas from the pressure source 28 to the SMPcells 18. Additionally or alternatively, various flexible or rigid tubesor any plumbing system may fluidly couple the SMP cells 18 with thepressurization system 20, providing inflation pressure to the SMP cells18.

Support Apparatus—Inflatable Cell Configuration

In an alternative embodiment of the invention, as illustrated in FIG. 4,the rigid structural member 16 may be a rigid sheet of material withopenings (not shown) formed therethrough at which the SMP cells 18 areattached to the rigid structural member 16. In these embodiments of theinvention, the rigid structural member 16 may be a flat or contouredrigid sheet of material or a hollow structure of various cross-sectionalshapes, such as a cylinder, a trapezoid, or any other cross-sectionalshape. In some embodiments of the invention, the rigid structural member16 may have a general shape corresponding to one or more surfaces orinner surfaces of the SMP apparatus 12.

As illustrated in FIG. 4, the SMP cells 18 may each be sealed to therigid structural member 16 around a periphery of one of the structuralmember openings such that liquid or pressurized gas forced through theseopenings inflate the SMP cells 18. For example, the SMP cells 18 and theopenings may be connected to the pressurization system 20, such as thetubes 26 and/or the pressure source 28, as illustrated in FIG. 3.

During inflation, SMP cells 18 may each increase in size and/or surfacearea independently by an amount dependent on their location relative toa surface of the SMP apparatus 12. In this embodiment of the invention,the SMP cells 18 may be configured to both flex and stretch when heatedabove T_(g). The SMP cells 18 of the configuration illustrated in FIG. 4may have any geometry and/or cross-section, such as a block, a cylinder,or a dome. For example, the SMP cells 18 may comprise a domed endconfigured to contact a surface of the SMP apparatus 12 when inflatedtherein.

Support Apparatus—Diaphragm Configuration

In another alternative embodiment of the invention, as illustrated inFIGS. 5-11, the SMP cells 18 may be SMP diaphragms. Furthermore, in someembodiments of the invention, the pressure source 28 may also act as avacuum source, such that the SMP cells 18 or diaphragms may be urgedinward through the openings in the rigid structural member 16. The SMPcells 18 or diaphragms may comprise a shape or configuration whichallows for inversion thereof via vacuum. For example, the SMP cells 18in this embodiment of the invention may be designed and fabricated to amaximum height required, based on target applications for the associatedsupport apparatus 10.

In some embodiments of the invention, the SMP cells 18 or diaphragms maybe formed of an SMP material which may flex when heated above T_(g), butnot necessarily stretch. For example, the SMP cells 18 may be formedwith a thickness and heated by such an amount during use that they maybe deployed outward with pressure and/or inverted inward by vacuumwithout stretching during deployment. Furthermore, the SMP cells 18 ordiaphragms may maintain a substantially constant surface area during usein either their deployed or inverted configurations.

The SMP cells 18 of the embodiments illustrated in FIGS. 5-11 maycomprise any shape or dimensions required for a given application, suchas a cylindrical, conical, or hemispherical shape. For example, asillustrated in FIGS. 7, 8 a, 8 b, and 10, the SMP cells 18 may have astepped-cup configuration, with a first cup section 32 and a second cupsection 34. Each of these cup sections may or may not have a taperedvolume. Furthermore, the first cup section 32 may have a greater minimumdiameter than a maximum diameter of the second cup section 34. Thestepped-cup configuration may also include additional cup sections, suchas a third and/or fourth cup section (not shown) arranged in a similarstepped configuration. The stepped-cup configuration of the SMP cells 18may allow for varying degrees of inversion by each cup section 32,34 andmay require less force for inversion of the SMP cells 18 than somealternative shapes and configurations. An alternative embodiment of theSMP cell in the stepped configuration, but with a less defined boundarybetween the cup sections, is illustrated in FIG. 9.

In one embodiment of the invention, illustrated in FIG. 10, one or moreof the SMP cells 18 may have an elongated or trough-like configuration,such that its length is substantially greater than its width.Furthermore, the elongated or trough-like SMP cells 18 may have astepped-trough configuration, such that the first portion 32 of the SMPcell 18 has a greater minimum length and/or width than the maximumlength and/or width of the second portion 34 of the SMP cell 18, asillustrated in FIG. 10. Note that the rigid structural member 16illustrated in FIG. 10 is merely an example. The rigid structural member16 illustrated with the elongated SMP cell 18 of FIG. 10 may be usedwith any rigid structural member 16, such as the rigid structuralmembers illustrated in FIGS. 5-6, without departing from the scope ofthe present invention.

The SMP cells 18 or diaphragms may also comprise a lip or attachmentportion 36 configured to seal the SMP cells 18 to a portion of the rigidstructural member 16, as illustrated in FIGS. 8 a and 8 b. Theattachment portion 36 may comprise SMP material and/or a rigid framecast with the SMP cells 18. For example, a frame of rigid epoxy may becast around each of the SMP cells 18. This frame or attachment portion36 may be configured to remain rigid while the SMP cell 18 is aboveT_(g), thereby providing a secure attachment or seal with the rigidstructural member 16 and/or the associated pressurization system 20, asdescribed below. The attachment portion 36 or frame may have any size orshape corresponding to a cross-sectional shape of the SMP cells 18.

In some embodiments of the invention, as illustrated in FIG. 5, therigid structural member 16 may comprise a rigid base component 38integral with or attached to a rigid tray 40 having a plurality ofopenings 42 formed therethrough. For example, the base component 38 maybe a cylinder, as illustrated in FIG. 5, and the tray 40 may surroundthe base component 38. Furthermore, the tray 40 may be supported a fixeddistance apart from the base component 38 by support elements 44. Forexample, the support elements 44 may be walls or dividers extendingalong a length of the base component 38 and extending between an outersurface of the base component 38 and an inner surface of the tray 40.

Additionally, the structural member 16 may comprise or be attached torigid containers 46 which may be aligned with the openings 42 of thetray 40 and fixed between the tray 40 and the base component 38. Thecontainers 46 may comprise a primary opening (not shown) aligned withthe tray openings 42 and/or an inflation opening (not shown) in fluidcommunication with the pressure source 28 via tubes 26. In thisconfiguration, the SMP cells 18 may be sealed to the containers 46 overthe primary opening thereof. For example, the attachment portion 36 ofthe SMP cells 18 may be sealed to the containers 46 and/or between thecontainers 46 and the tray 40. Furthermore, the SMP cells 18 may behoused in the containers 46 in an inverted configuration (when vacuumpulls the SMP cells 18 away from the SMP apparatus 12), and pushedoutward from within the containers 46 in a deployed configuration (whensupplied with liquid or pressurized gas forced through the inflationopenings of the containers 46).

The height of the SMP cells 18 in this embodiment of the invention maybe approximately equal to the greatest distance between the tray 40 andthe SMP apparatus 12. Furthermore, the distance between the tray 40 andthe base component 38 may be approximately equal to the height of theSMP cells 18. Additionally or alternatively, a depth of the containers46 may be approximately equal to the height of the SMP cells 18, suchthat each of the SMP cells 18 may be fully inverted within theircorresponding containers 46.

As in the previous embodiments of the invention described above, thesupport apparatus 10 of FIGS. 5-11 may also comprise the pressurizationsystem 20 comprising tubes 26 and the pressure source 28, as illustratedin FIG. 3. One or more of the tubes 26 may also include a valve (notshown) which may be opened or closed manually or by some other actuatingmeans. In some embodiments of the invention, each of the containers 46may be associated with one of the valves, so that if one of the SMPcells 18 or diaphragms tears or unseals from its container 46, the otherSMP cells 18 connected to the same tube 26 or line may still operateproperly. Furthermore, in some embodiments of the invention, each of theSMP cells 18 may be vented such that newly-heated liquid, air, or gasmay be continuously circulated through the SMP cells 18 during a givenheating cycle or inflation cycle.

Methods of Use

In use, the SMP apparatus 12 may be heated and pressurized or otherwiseformed into a desired shape. Then the support apparatus 10 may beinserted into the SMP apparatus 12 or arranged proximate thereto suchthat inflation or deployment of the SMP cells 18 causes the SMP cells 18to contact at least one surface of the SMP apparatus 12. In someembodiments of the invention, the SMP apparatus 12 may be placed into arigid outer mandrel tool (not shown) or clam shell, heated, and theninflated or deployed therein. Then the support apparatus 10 may beinserted into the SMP apparatus 12 and the SMP cells 18 may be heat andinflated or deployed while the SMP apparatus 12 remains in the outermandrel tool. This may cause the SMP apparatus 12 to be sandwichedbetween the SMP cells 18 and the outer mandrel tool. Additionally oralternatively, the support apparatus 10 may be built into or onto theSMP apparatus 12 and the SMP apparatus 10 and SMP cells 18 may besimultaneously or sequentially deployed or inflated during a single heatcycle using an oven or autoclave to heat the SMP components.

In some alternative embodiments of the invention, inflating of the SMPapparatus 12 may be omitted. Rather, the inflation of the SMP cells 18therein may push the SMP apparatus 12 outward against the outer mandreltool. In another alternative embodiment of the invention, the SMPapparatus 12 may be formed or inflated into the desired shape within amold while the SMP cells 18 are simultaneously inflated against asurface of the SMP apparatus. In yet another alternative embodiment ofthe invention, the SMP apparatus 12 may be in a rigid state and/orremoved from the outer mandrel tool before the SMP cells 18 are heatedand inflated therein, such that the SMP cells 18 may conform to theinner surface of the SMP apparatus 12 in its rigid mandrel state.

In some embodiments of the invention, such as those illustrated in FIGS.1-3, use of the support apparatus 10 may further comprise actuating theextension support members 24 toward and/or away from the central supportstructure 22 once the support apparatus 10 is positioned inside the SMPapparatus 12, thus providing internal support for SMP apparatuses ofdifferent diameters or different shapes and configurations. For example,the extension support members 24 may be adjusted prior to inflation ordeployment of the SMP cells 18.

After inflation or deployment of the SMP cells 18 against the SMPapparatus 12, the SMP cells 18 may be cooled and thereby hardened intheir inflated state, as illustrated in FIGS. 2, 8 a, and 11. The SMPcells 18 provide a load path between the rigid structural member 16 andthe SMP apparatus 12 while the composite material 14 is applied thereon.After the composite material 14 is cured, the SMP bladders 18 and/or theSMP apparatus 12 may remain heated above T_(g) or be otherwise triggeredinto the malleable state, such that they may be deflated or inverted, asillustrated in FIG. 8 b, to be removed from within the resulting curedcomposite part.

In some embodiments of the invention, such as those illustrated in FIGS.1-3, if the extension support members 24 were lengthened or extendedaway from the central support structure 22 before inflation of the SMPbladders 18, the extension support members 24 may be shortened orretracted toward the central support structure 22 in order to haveenough clearance within the cured composite part to remove the supportapparatus 10.

In the embodiments of the invention illustrated in FIGS. 5-11, vacuummay be applied by the pressurization system 20 while the SMP cells 18are still in the malleable state. Thus, the SMP cells 18 may be invertedinto their corresponding containers 46 through the openings 42 in thetray 40, providing clearance for the support apparatus 10 to be removedfrom within the SMP apparatus 12 and/or the resulting composite part. Inother embodiments of the invention, as illustrated in FIGS. 1 and 4, theSMP cells 18 may be deflated to provide the proper clearance for removalfrom within the cured composite part.

Note that the inflation and/or vacuum described herein may be replacedwith or provided in addition to any means for creating a pressuredifferential known in the art. For example, pressure for inflating ordeflating the SMP apparatus 12 and/or the SMP cells 18 may be providedvia an autoclave or any other system capable of inflating or deflating asealed malleable material. Furthermore, though the support apparatus 10is described herein as providing structural support for the SMPapparatus 12, note that the support apparatus 10 may also be used toprovide structural support to any molding or mandrel tooling used toform composite parts.

Although the invention has been described with reference to thepreferred embodiments illustrated in the attached drawing figures, it isnoted that equivalents may be employed and substitutions made hereinwithout departing from the scope of the invention as recited in theclaims.

Having thus described various embodiments of the invention, what isclaimed as new and desired to be protected by Letters Patent includesthe following:
 1. A support apparatus configured for providing internalsupport to a mold, tooling, or SMP apparatus for forming compositeparts, the support apparatus comprising: a rigid structural member thatremains rigid when heated to a temperature sufficient for curing acomposite part; a plurality of deployable SMP cells made of shape memorypolymer (SMP) configured to be actuated to transition between a rigidstate and a malleable state; a pressurization system configured todeploy the SMP cells to extend from the rigid structural member when inthe malleable state; wherein the rigid structural member has a pluralityof openings formed therethrough and aligned with the SMP cells, whereinthe SMP cells are each in fluid communication with the pressurizationsystem and are configured to deploy through the openings formed throughthe rigid structural member and to transfer load to the rigid structuralmember; and wherein the SMP cells are actuatable via the pressurizationsystem between an inverted configuration in which the SMP cells extendfrom the rigid structural member in a first direction and a deployedconfiguration in which the SMP cells are driven through the openings ina second direction opposite of the first direction.
 2. The supportapparatus of claim 1, wherein the SMP cells are configured to be in therigid state at a temperature below T_(g) and to become malleable at atemperature above T_(g).
 3. The support apparatus of claim 2, whereinthe pressurization system comprises a pressure source and a heatexchanger configured to force heated or cooled liquid or gas into orthrough the SMP cells to actuate the SMP cells from the rigid state tothe malleable state or from the malleable state to the rigid state. 4.The support apparatus of claim 1, wherein the SMP cells each comprise anattachment portion at which the SMP cell is attached to the rigidstructural member, wherein the attachment portion is configured toremain rigid while the remainder of the SMP cell is in the malleablestate.
 5. The support apparatus of claim 1, wherein the rigid structuralmember comprises a base component and a tray supported by and fixedlyspaced apart from the base component, wherein the plurality of openingsof the rigid structural member are formed through the tray.
 6. Thesupport apparatus of claim 1, further comprising a plurality of rigidcontainers fixed between the base component and the tray, the containerseach having a first opening aligned with the openings formed through thetray and a second opening in fluid communication with the pressurizationsystem, wherein the SMP cells extend within the containers in theinverted configuration and extend at least partially outward of thecontainers in the deployed configuration.
 7. The support apparatus ofclaim 1, wherein the SMP cells are configured to be flexible in themalleable state and to not stretch or increase in surface area whenactuated by the pressurization system to deploy.
 8. The supportapparatus of claim 1, wherein the SMP cells comprise a first portion anda second portion arranged in a stepped configuration, such that across-section of the first portion encompasses a greater area than across-section of the second portion.
 9. The support apparatus of claim1, wherein at least some of the SMP cells are elongated, having a lengthgreater than a width and a height thereof.
 10. The support apparatus ofclaim 1, wherein the pressurization system comprises a pressure source,a plurality of tubes through which pressurized gas from the pressuresource may flow to the SMP cells, and a plurality of valves configuredto independently control pressurization of one or more of the SMP cells.11. An apparatus forforming composite parts, wherein the apparatuscomprises: an SMP apparatus formed of shape memory polymer (SMP), havingan inner surface and an outer surface, wherein the outer surface of theSMP apparatus is shaped and configured to form an inner surface of thecomposite part; and a support apparatus in contact with the innersurface of the SMP apparatus, the support apparatus comprising: a rigidstructural member that remains rigid when heated to a temperaturesuitable for curing a composite part; a plurality of hollow deployableSMP cells made of shape memory polymer (SMP) and configured to be rigidat temperatures below T_(g) and to become malleable at temperaturesabove T_(g), wherein the SMP cells are attached to the rigid structuralmember and contact the inner surface of the SMP apparatus; and apressurization system configured to pressurize the SMP cells, such thatthe SMP cells are actuated to press away from the rigid structuralmember and against the SMP apparatus when heated to a temperature aboveT_(g), wherein the SMP cells are actuatable via the pressurizationsystem between an inverted configuration in which the SMP cells extendfrom the rigid structural member in a first direction and a deployedconfiguration in which the SMP cells are driven outward to extend fromthe rigid structural member in a second direction opposite of the firstdirection, wherein the SMP cells provide a rigid load path between theSMP apparatus and the rigid structural member when cooled below T_(g)while pressed against the inner surface of the SMP apparatus.